I've got an 02 F350 4WD I bought used a couple of years ago. The VC label code says that it has a 3.73 Limited slip rear end. However, I have gotten stuck in loose sand out at my place in the country several times. It seems like it is usually the right rear that breaks loose and spins free. I end up having to pul it free with my tractor. Any idea why the limited slip doesn't work? (BTW this happens in both 4WD and 4WD low)

 

Clutches are shot or there's too much friction modifier in it, also those units need some resistance on both sides to work so if it works on other surfaces there is nothing wrong with it. The right breaks loose because the torque raises that side up.

 

Could be bad clutches or just no traction. Apply the parking brake to "create" traction in those situations. It will get both wheels turning.

 

Thanks for the input from both of you. Guess I'll go and try the parking brake solution and if that doesn't help i'll get the rear checked out.

 

Change the fluid, start with no friction modifier and see how the LS behaves.

 

Guess I'll change the fluid later today.